Arrangement for holding together a turbine rotor and other aligned members of a gas turbine

ABSTRACT

The invention comprises an improved design of a radial gas turbine assembly that is held together by a bolt secured to the turbine rotor and extending through a bore in members aligned with the rotor, the bolt having no centering contact with the walls of the bore, at least in the portion adjacent the turbine rotor. The connection between the bolt and the turbine rotor comprises a hollow sleeve of a heat resistant material that is a relatively poor conductor of heat, said sleeve having a clearance with respect to the bore in the order of 0.05 mm. The sleeve is connected to the bolt and to a pin protruding from the turbine rotor in such a way that the ends of the pin and the bolt respectively are kept a substantial distance apart.

United States Patent Andvig Feb. 15,1972

[72] Inventor:

[73] Assignee:

Tore Anton Andvig, Kongsberg, Norway A/S Kongsberg Vapenfabrikk,Kongsberg, Norway 221 Filed: Nov. 25, 1969 211 AppLNoL: 879,817

Judson et a1. ..415/177 X Castle 3,424,433 l/ 1969 Langshur ..416/237FOREIGN PATENTS OR APPLICATIONS 248,083 1/1948 Switzerland ..4 1 6/ 244269,605 10/ 1950 Switzerland ..4 16/244 Primary Examiner-Everette A.Powell, Jr. Attorney-Holman 8!. Stem [57] ABSTRACT 30] ForeignApplication p i i Data The invention comprises an improved design of aradial gas turbine assembly that is held together by a bolt secured tothe NOV. 25, 1968 Norway ..4691/68 turbine rotor and extending through abore in members aligned with the rotor, the bolt having no centeringcontact [52] US. Cl. ..416/183, 416/244 with the walls of the bore atleast in the portion adjacent the [51] Int. Cl ..F0ld 5/04,F01d 5/06turbine mum The connection between the bolt and the mp [5 8] Field ofSearch 21: bine rotor comprises a hollow sleeve of a heat resistantmaterial that is a relatively poor conductor of heat, said sleeve havinga clearance with respect to the bore in the order of 0.05 [56]References Cited mm. The sleeve is connected to the bolt and to a pinprotrud- UNITED STATES PATENTS ing from the turbine rotor in such a waythat the ends of the pm and the bolt respectively are kept a substantialdistance 2,308,233 1/1943 Schutte ..415/ 177 apart 2,577,134 12/1951Land ..416/244 2,843,311 7/1958 Buchi ..416/244 X 3 Claims, 1 DrawingFigure I l Q PATENTEUFEB 15 m2 3.642.383

INVENTOR file ,9. 191m w'G- BYM M,

ATTORNEYS BACKGROUND OF THE INVENTION The present invention relates toan arrangement for holding together a turbine rotor and other alignedmembers of a gas turbine by means of an elongated connecting elementsecured to the rotor, extending coaxially with said members through abore therein and forcing the members axially together, the turbine rotorand the adjacent member being centered with respect to each other bymeans other than the connecting element.

Since the connecting element, which may for instance consist of a bolt,is secured to the turbine rotor, which is in contact with the hot gases,and since, due to the fact that the turbine rotor and the adjacentmember are centered with respect to each other by other means, the boltmust have a clearance with respect to the bore in the adjacent member,heat from the turbine rotor will be conducted through the bolt, which istherefore strongly heated. This heating of course causes an axialexpansion of the bolt and thereby a reduction in the clamping forcebetween the members.

SUMMARY OF THE INVENTION The object of the invention is to provide aconnecting arrangement as indicated, in'which the heat from the turbinerotor is to a substantial extent prevented from being conducted throughthe bolt-shaped connecting element, whereby the disadvantages connectedwith the heating of the bolt are eliminated.

This is achieved due to the fact that the connection between theconnecting element and the rotor comprises a portion having aheat-insulating core and a very small clearance with respect to the borein the said adjacent member and also a length that is so proportioned tothe clearance that a substantial part of the heat supplied from theturbine rotor is transferred to the said adjacent member.

A heat-insulating core may be provided for instance by shaping the saidportion as a separate sleeve with a hollow core. The clearance betweenthe sleeve and the bore may for instance be 0.05 mm., and the length ofthe heat-insulating core portion may be of the same magnitude as thediameter of this portion. In this manner the heat conducted from theturbine rotor will be forced towards the walls of the bore in the saidadjacent member, which may for instance be a compressor rotor, whereby asubstantial part of the heat will be directed to the hub of thecompressor rotor instead of being carried off through the connectingelement.

The insulating connecting sleeve may advantageously be made of a heatresistant material that is a relatively poor conductor of heat, such asNimonic 90, which is also the preferred material for the turbine rotor.

The sleeve may, for instance by screw threads, be connected at one endto a pin protruding from the turbine rotor and at the other end to theconnecting element, which is in the form of a bolt. The ends of the pinand the connecting bolt must then of course be located a substantialdistance apart in order to leave a heat-insulating core in accordancewith the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the inventionwill now be described in more detail, reference being had to theaccompanying drawing, which is a section of an axial sectional view of aradial gas turbine.

In the drawing, 1 is a radial turbine rotor having blades 2 andpropelled by the hot gases from a combustion chamber. A compressor rotorconsisting of two parts 4 and 5, each having a hub 6 and 7,respectively, and blades 8 and 9, respectively, is positioned coaxiallywith and adjacent the turbine rotor l. The hub 7 of one part of thecompressor rotor is provided with a shaft portion 10 which in a mannernot illustrated is operatively connected to a coupling end 11 which maybe coupled to a shaft of a reduction gear. The turbine rotor l, the twoparts 4 and 5 of the compressor rotor, an intermediate bearing sleevenot illustrated, and the coupling member 11 are held together into astack by means of a longitudinal bolt 12 secured to the turbine rotor land a nut 13. The connecting bolt 12 extends through a central bore inthe coupling member 11, the shaft portion 10 and the hub 7.

The connecting bolt 12 is secured to the turbine rotor 1 through asleeve 14. The connecting bolt 12 threadedly engages one end of thesleeve 14, which at the other end threadedly engages a pin 15 on theturbine rotor 1. The end faces of the connecting bolt 12 and thethreaded pin 15 are spaced by a substantial distance so that in theconnection between the bolt 12 and the rotor 1 there is provided a heatinsulating core in the form of a cavity 16.

The compressor rotor and the turbine rotor I are connected to each otherin a force-transmitting relationship by means of a known tooth coupling17, which is designed so as to effect also a centering of the rotorswith respect to each other. The rotors are forced together by tensioningthe bolt 12. Since, as stated, the tooth coupling 17 centers the rotorson each other, the sleeve 14 must have a clearance with respect to thebore in the hub 7. However, according to the invention great importanceis attached to making this clearance as small as possible, for instancein the order of 0.05 mm, which requires a careful working of the bore aswell as the sleeve with small tolerances and correspondingly high costs.However, together with a suitable length of the cavity 16, such aclearance will cause a substantial part of the heat conducted from therotor 1 through the pin 15 and into the sleeve 14 to pass into the hub 7instead of entering the bolt 12. By a given length of the cavity 16 thiseffect is enhanced if a material that is a poor conductor of heat isused for the sleeve 14. At the same time the material of the sleeve 14must be heat resistant. A material meeting these requirements is forinstance Nimonic 90, which can also be used for the rotor l.

I claim:

1. A turbine rotor assembly comprising a turbine rotor and a compressorrotor connected in a force-transmitting relationship; said compressorrotor comprising a hub having a shaft portion, said hub and shaftportion having an axial bore therethrough; a coupling member operativelyconnected to said shaft portion and coaxial therewith; sleeve meanswithin said bore and coaxial therewith, said sleeve means being heatresistant and a poor conductor of heat, and having a heat-insulatingcavity therein; said turbine rotor having a pin thereon fixedly securedto one end of said sleeve means and coaxial therewith; and alongitudinal connecting element fixedly secured at one end to saidcoupling member and at the other end to the other end of said sleevemeans, and coaxial therewith; said sleeve means having a close tolerancewith respect to said bore.

2. A turbine rotor assembly according to claim 1 wherein

1. A turbine rotor assembly comprising a turbine rotor and a compressorrotor connected in a force-transmitting relationship; said compressorrotor comprising a hub having a shaft portion, said hub and shaftportion having an axial bore therethrough; a coupling member operativelyconnected to said shaft portion and coaxial therewith; sleeve meanswithin said bore and coaxial therewith, said sleeve means being heatresistant and a poor conductor of heat, and having a heat-insulatingcavity therein; said turbine rotor having a pin thereon fixedly securedto one end of said sleeve means and coaxial therewith; and alongitudinal connecting element fixedly secured at one end to saidcoupling member and at the other end to the other end of said sleevemeans, and coaxial therewith; said sleeve means having a close tolerancewith respect to said bore.
 2. A turbine rotor assembly according toclaim 1 wherein said pin and said connecting element are threadedlysecured to said sleeve means, and are separated from each other by saidcavity.
 3. A turbine rotor assembly according to claim 1 wherein saidcavity is of a length which, in proportion to said tolerance, causestransfer to said hub of a substantial portion of the heat supplied tothe sleeve from the turbine rotor.